The concept of harvest index as applied to Hevea

Gomez J. B., . and Sivanadyan K., . and Leong S. K., . and Ghandimathi H., . The concept of harvest index as applied to Hevea. pp. 86-92. ISSN 0127-7065

The concept of harvest index for measuring productivity of Hevea has not been generally used hitherto. In the present study an attempt is made to obtain and compare values of harvest indices for various Hevea species a series of Hevea brasiliensis clones and finally for a specific high-yielding Class I clone. Some physiological and structural parameters related to yield and hence ultimately to the harvest index are also considered. From the study it is apparent that among the Hevea species the harvest index is highest for Hevea brasiliensis. Individuals in a population of seedling trees of Hevea also vary in their harvest indices. Clonal variation and annual variation are clearly evident. Variation due to age is also apparent. Competition between trees and the partition of assimilates between the competing physiological sinks within trees are factors which affect tree growth and hence productivity of rubber. The efficiency of the source may be assumed to be variable especially as influenced by clonal character age and perhaps other physiological parameters including those influencing tree-to-tree competition. It is noted that the variability of the sink may also influence these physiological parameters through the influences on water turn-over and the variability in biosynthetic capacity of the laticiferous system. Exploitation procedures can also be expected to influence the behaviour of the sink and its efficiency. The concept of harvest index therefore might be a very useful property not only for comparison of clones but also to measure sensitivity of the clone to exploitation procedures and other environmental factors.

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Abstract

The concept of harvest index for measuring productivity of Hevea has not been generally used hitherto. In the present study an attempt is made to obtain and compare values of harvest indices for various Hevea species a series of Hevea brasiliensis clones and finally for a specific high-yielding Class I clone. Some physiological and structural parameters related to yield and hence ultimately to the harvest index are also considered. From the study it is apparent that among the Hevea species the harvest index is highest for Hevea brasiliensis. Individuals in a population of seedling trees of Hevea also vary in their harvest indices. Clonal variation and annual variation are clearly evident. Variation due to age is also apparent. Competition between trees and the partition of assimilates between the competing physiological sinks within trees are factors which affect tree growth and hence productivity of rubber. The efficiency of the source may be assumed to be variable especially as influenced by clonal character age and perhaps other physiological parameters including those influencing tree-to-tree competition. It is noted that the variability of the sink may also influence these physiological parameters through the influences on water turn-over and the variability in biosynthetic capacity of the laticiferous system. Exploitation procedures can also be expected to influence the behaviour of the sink and its efficiency. The concept of harvest index therefore might be a very useful property not only for comparison of clones but also to measure sensitivity of the clone to exploitation procedures and other environmental factors.

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Item Type:	Article
AGROVOC Term:	Hevea brasiliensis
AGROVOC Term:	Hevea
AGROVOC Term:	Species differences
AGROVOC Term:	Clones
AGROVOC Term:	High yielding varieties
AGROVOC Term:	Seedlings
AGROVOC Term:	Harvest index
AGROVOC Term:	Crop production
AGROVOC Term:	Clonal variation
AGROVOC Term:	Environmental factors
Geographical Term:	Malaysia
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	28 Apr 2025 04:44
URI:	http://webagris.upm.edu.my/id/eprint/23522

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